The invention relates generally to strain relieving a cable, and more particularly, to strain relieving a communications cable having a non-cylindrical cross section, such as a flat cable or an elliptical cable.
Communications cables typically have a cylindrical (i.e., circular) cross section. Communications cables having a cylindrical cross section can be strain relieved by a number of conventional strain relief apparatus and methods developed for clamping cylindrical hoses. Typical apparatus and methods for strain relieving cylindrical hoses include clamping the hose between a semi-circular strap and a flat plate and surrounding the hose with a hose clamp or other circular restraint that is secured to a stationary surface and tightened around the exterior of the hose.
Recently developed communications feeder and drop cables have a non-cylindrical cross section, and thus, require an apparatus and method of strain relief. The previously known strain relief apparatus and methods are effective for gripping cylindrical cables, but are less effective when used to grip cables having a non-cylindrical cross section, and in particular, flat cables and elliptical cables. Furthermore, the previously known strain relief apparatus and methods optimally position cylindrical cables, but do not provide for optimally positioning cables having a non-cylindrical cross section. The major axis dimension of flat cables and elliptical cables limits the number of cables that can be laid side-by-side in a planar orientation on a strain relief apparatus having a predetermined lateral dimension. In particular, the number of cables that can be positioned in a planar orientation is limited by the distance between the fasteners used to apply the compressive force to the cables or by the dimensions of the base of the enclosure in which the cables are strain relieved.
An apparatus is provided for strain relieving a cable having a non-cylindrical cross section. The apparatus includes at least two adjacent plates, each of the plates having at least one mounting surface and at least one strain relief surface. The strain relief surface may be angled relative to the mounting surface. Fasteners draw the plates together to grip the cable between the opposed strain relief surfaces of the adjacent plates. In addition to strain relieving cables having a non-cylindrical cross section, the apparatus optimally positions the cables to increase the number of cables that can be positioned on an apparatus having a predetermined lateral dimension or within the dimensions of the base of an existing enclosure.
The invention includes several embodiments of the apparatus. The plates may have one or more mounting surfaces and one or more strain relief surfaces. The plates may have a mechanical stop located between each pair of opposed mounting surfaces. The stops maintain a minimum distance between the strain relief surfaces, and thereby prevent the cables from being crushed and damaged in the event that the fasteners are over-tightened.
In an alternative embodiment, the plates each have a flat base surface that functions as both a mounting surface and a strain relief surface. Similarly, the plates each have mechanical stops that abut the underside of the base surface of the adjacent plate.
In yet another alternative embodiment, each plate has a plurality of laterally extending teeth provided on the lengthwise edges of the strain relief surfaces or the base surfaces. The teeth grip the cable securely therebetween and, in addition, may ground a cable having an electrically conductive inner sheath.
In each embodiment, a plurality of plates may be assembled together to strain relieve more cables than can be accommodated between only two adjacent plates. If so, assembled, each fastener will pass through a mounting surface of each of the plurality. of plates to secure the cables between the plates.